This invention relates to a combinatorial weighing system and, more particularly, to an improvement in a method of supplying weighing hoppers with articles to be weighed, wherein a pool tray corresponding to each of a plurality of weighing hoppers is disposed between the weighing hopper and a supply table where articles are pooled in advance, articles received from the supply table are temporarily pooled on each of the pool trays, and those pool trays corresponding to emptied weighing hoppers that have discharged their articles in combination are actuated to automatically resupply the empty weighing hoppers anew.
A combinatorial weighing apparatus is designed to dispense batches of articles, each batch having a predetermined weight or a predetermined number of the articles. The apparatus, which includes a plurality of weighing machines, operates by weighing out small quantities of the articles using the weighing machines, each quantity having a slightly different weight value from the others, combining these weight values into a multiplicity of different combinations, or converting each weight value into the number of articles giving said weight value and then combining these article numbers into a multiplicity of combinations, adding the weight values or article numbers in each combination to obtain the corresponding sums, selecting the combination giving a sum equal to a preset weight or preset number, discharging the articles from the weighing machines corresponding to the selected combination, and collecting these discharged articles together into a single batch having the preset weight or preset number of articles. Such a weighing apparatus enables a highly accurate weighing operation to be carried out.
The construction of an automatic combinatorial weighing apparatus for performing such weighing is illustrated in FIG. 1. The combinatorial weighing apparatus includes a dispersing table 1 supported on an electromagnetic vibrating device 2 so as to be subjected to helical reciprocatory vibration, a plurality of supply troughs 3 disposed radially about the dispersing table 1, a plurality of electromagnetic vibrating devices 4 for vibrating corresponding ones of the supply troughs 3, a light-emitting device 5 supported on a post 6, and a light-receiving device 5' supported on a post 6', these devices serving to optically detect the quantity of articles accumulated on the dispersing table 1. The combinatorial weighing apparatus further includes a plurality of pool hoppers 7, each of which is situated below the distal end of a corresponding one of the supply troughs 3, a plurality of weighing hoppers 8 provided below corresponding ones of the pool hoppers 7, and a plurality of weighing machines 9, each supporting one of the weighing hoppers 8. Each pool hopper 7 is provided with a lever mechanism 10 for opening and closing the pool hopper, and each weighing hopper 8 is provided with a lever mechanism 11 for opening and closing the hopper. A drive mechanism 12 is provided for each pair of the hoppers 7, 8. The combinatorial weighing apparatus has a collecting chute 13 for collecting articles discharged from the weighing hoppers 8.
The automatic combinatorial weighing apparatus thus constructed operates as follows.
The articles are supplied automatically from the distributing table 1 through the supply troughs 3 into pool hoppers 7 and thence into the corresponding weighing hoppers 8. The articles thus received in the weighing hoppers 8 are weighed by the weighing machines 9 associated therewith. Based on the weights measured by the weighing machines 9, a control unit, not shown, combines the weight values into an arbitrary or predetermined number of combinations, computes the sum of the weight values in each combination, compares each sum with a preset weight, and selects the combination that gives a sum, total weight, equal to the target weight. The control unit then operates to open the weighing hoppers 8, which correspond to the selected combination, by the operation of the lever mechanisms 11 so that the articles are released into the collecting chute 13 from the weighing hoppers 8 to be collected together into a batch and discharged into a packaging machine or a bucket conveyor, not shown. This will leave the selected weighing hoppers 8 empty. Articles are then newly delivered from the corresponding pool hoppers 7, supplied with the articles in advance, into the empty weighing hoppers 8 by actuating the lever mechanisms 10, leaving these pool hoppers 7 empty, whereupon a new supply of articles is delivered from the dispersing table 1 and the corresponding supply troughs 3 by actuating the associated vibrating devices. The automatic combinatorial weighing operation can be continued in this manner by repeating the foregoing steps.
Thus, the articles are supplied to the weighing hoppers through the pool hoppers after accumulating temporarily on the dispersing table and in the supply troughs. Since the weighing machines are situated remote from the dispersing table, the articles dispensed by the dispersing table inevitably travel a long distance to reach the weighing hoppers. In consequence, articles such as chocolates or biscuits tend to be damaged by striking one another while in transit from the dispersing table to the weighing hoppers, resulting in a product of reduced commercial value. Moreover, viscous articles such as meats, pickles, fish and vegetables, as well as articles that are large in size and irregular in shape, have a greater opportunity of attaching themselves to the surface of the equipment when the path traversed is long. Obviously, articles that remain in the path of transit will not reach the weighing hoppers and, if such articles are large in size, eventual blockage of the path may result.
To prevent soft and delicate articles from being damaged or deformed, and to assure that large or viscous articles will be fed into the weighing hoppers in reliable fashion, a common arrangement adopted recently is to provide a supply table immediately above the weighing hoppers and introduce the articles into the weighing hoppers of the weighing machines directly from the table by a manual operation. Then, after a combinatorial weighing cycle is performed, the articles are discharged automatically into a collecting conveyor from the selected weighing hoppers. This arrangement is called semiautomatic combinatorial weighing apparatus, and it has been developed recently.
The foregoing arrangement has a number of drawbacks. Specifically, the supply table is mounted on a frame so as to overlay the plurality of weighing hoppers, which are provided on a machine frame, the table lying parallel to the weighing hoppers and extending to the outer side of each hopper. To load articles from the supply table into the inner reaches of the weighing hoppers, an operator must stand on a pedestal provided on the outside of the frame. Consequently, in order to detect, on the basis of a signal, the weighing hoppers that have been emptied by discharging their articles in a combinatorial weighing cycle, the operator, standing on the pedestal, must lean forward from above the supply table and confirm whether there are articles in the weighing hoppers located below the supply table. This is an extremely troublesome task. The ensuing task of loading articles into the emptied weighing hoppers by hand is also a difficult one for the operator. In performing this activity, moreover, the operator may inadvertently cause articles to fall from the supply table into weighing hoppers which, at the end of a weighing cycle, have yet to discharge their articles. This will cause articles to be packaged in excess of the prescribed weight or number.